private static List<EdgeAggregator> CheckAndGenerateProportionality(Triangle tri, Intersection inter1,
Intersection inter2, Parallel parallel)
{
List<EdgeAggregator> newGrounded = new List<EdgeAggregator>();
// The two intersections should not be at the same vertex
if (inter1.intersect.Equals(inter2.intersect)) return newGrounded;
//
// Do these intersections share a segment? That is, do they share the transversal?
//
Segment transversal = inter1.AcquireTransversal(inter2);
if (transversal == null) return newGrounded;
//
// Is the transversal a side of the triangle? It should not be.
//
if (tri.LiesOn(transversal)) return newGrounded;
//
// Determine if one parallel segment is a side of the triangle (which must occur)
//
Segment coinciding = tri.DoesParallelCoincideWith(parallel);
if (coinciding == null) return newGrounded;
// The transversal and common segment must be distinct
if (coinciding.IsCollinearWith(transversal)) return newGrounded;
//
// Determine if the simplified transversal is within the parallel relationship.
//
Segment parallelTransversal = parallel.OtherSegment(coinciding);
Segment simpleParallelTransversal = new Segment(inter1.intersect, inter2.intersect);
if (!parallelTransversal.IsCollinearWith(simpleParallelTransversal)) return newGrounded;
// A
// /\
// / \
// / \
// off1 /------\ off2
// / \
// B /__________\ C
//
// Both intersections should create a T-shape.
//
Point off1 = inter1.CreatesTShape();
Point off2 = inter2.CreatesTShape();
if (off1 == null || off2 == null) return newGrounded;
// Get the intersection segments which should coincide with the triangle sides
KeyValuePair<Segment, Segment> otherSides = tri.OtherSides(coinciding);
// The intersections may be outside this triangle
if (otherSides.Key == null || otherSides.Value == null) return newGrounded;
Segment side1 = inter1.OtherSegment(transversal);
Segment side2 = inter2.OtherSegment(transversal);
// Get the actual sides of the triangle
Segment triangleSide1 = null;
Segment triangleSide2 = null;
if (side1.IsCollinearWith(otherSides.Key) && side2.IsCollinearWith(otherSides.Value))
{
triangleSide1 = otherSides.Key;
triangleSide2 = otherSides.Value;
}
else if (side1.IsCollinearWith(otherSides.Value) && side2.IsCollinearWith(otherSides.Key))
{
triangleSide1 = otherSides.Value;
triangleSide2 = otherSides.Key;
}
else return newGrounded;
// Verify the opposing parts of the T are on the opposite sides of the triangle
if (!triangleSide1.PointLiesOnAndExactlyBetweenEndpoints(off2)) return newGrounded;
if (!triangleSide2.PointLiesOnAndExactlyBetweenEndpoints(off1)) return newGrounded;
//
// Construct the new proprtional relationship and resultant equation
//
Point sharedVertex = triangleSide1.SharedVertex(triangleSide2);
SegmentRatio newProp1 = new SegmentRatio(new Segment(sharedVertex, off2), triangleSide1);
SegmentRatio newProp2 = new SegmentRatio(new Segment(sharedVertex, off1), triangleSide2);
GeometricSegmentRatioEquation newEq = new GeometricSegmentRatioEquation(newProp1, newProp2);
// Construct hyperedge
List<GroundedClause> antecedent = new List<GroundedClause>();
antecedent.Add(tri);
antecedent.Add(inter1);
antecedent.Add(inter2);
antecedent.Add(parallel);
newGrounded.Add(new EdgeAggregator(antecedent, newEq, annotation));
return newGrounded;
}